Field of the Invention
The invention relates to a guide apparatus for guiding sheets to a sheet-processing machine.
Sheet-processing machines are known, such as printing machines in which an underlapped stream of sheets is fed over a feed table to an acceleration system belonging to the machine. In this case, a sheet is drawn off the feed table and accelerated, while the sheet located underneath is being aligned and quietened at front lays or front top lays in the sheet transport and lateral directions. The sheet can be influenced so severely by the sheet running out that, for example, it shoots over the front lays or front top lays and runs with it into the machine. In order to separate this “imbricated formation”, that is to say the sheets overlapping each other, a guide apparatus is used such as is disclosed by German Patent DE 296 15 996 U1, for example. The guide apparatus disposed above the feed table deflects the outgoing sheet in such a way that a large separating angle is produced between the feed table and the sheet running out over the front top lay, so that the sheet located underneath is guided reliably under the top lays.
Depending on the printing-material thickness, the printing-material stiffness, the sheet format and the machine speed, the distance between the guide apparatus and the feed table and, in the paper running direction, the front lays or front top lays can be adjusted. The guide apparatus has a stable shaft which is continuous over the feed table and impairs the accessibility of the machine operator to the front lays, for example to remove a misfed sheet or to set the print-free margin. In addition, it has proven to be disadvantageous that it is not possible to ensure the reliable entry of the first sheet of a stream of sheets, in particular in the case of thick printing materials which are very wavy at the sheet leading edge, in all cases to the guide apparatus or, respectively, to the front lays/front top lays.